This application is a continuation of the applicant's long-term efforts to elucidate the cellular and molecular pathways in the pathogenesis of chronic kidney diseases (CKD), most of which originates from glomerular lesions. Proteinuria, resulting from defective glomerular filtration, is an early hallmark and principal pathologic feature of a large number of CKD. Although podocyte dysfunction is known to play a critical role in the onset of proteinuria, the underlying mediators, signaling pathways and mechanisms remain poorly defined. Recent studies from the applicant's laboratory have linked the aberrant b-catenin signaling to podocyte injury and proteinuria. The central hypotheses of this application are that: b-catenin activation plays an imperative role in mediating podocyte dysfunction and proteinuria; and therefore inhibition of this signaling by small molecule inhibitor (ICG-001) provides a novel approach for therapeutic intervention of proteinuric kidney diseases. The overall goal of this application is to delineate the role of 2- catenin and its downstream target MMP-7 in the pathogenesis of podocyte injury and proteinuria and to explore the feasibility of targeting 2-catenin signaling for therapeutic intervention. In Aim 1, we will evaluate the feasibility and efficacy of targeted inhibition of 2-catenin by a novel small molecule in three models of proteinuric kidney diseases. In Aim 2, we will investigate the mechanism underlying the pathogenic actions of 2-catenin and explore how inhibition of 2-catenin leading to protection of podocyte integrity in vitro. Finally, we will focus on one major target of 2-catenin, MMP-7, and investigate its role in the pathogenesis of proteinuria in Aim 3. These studies will likely offer fundamental and important insights into understanding of the patho-mechanism of proteinuria, and could provide a foundation for the exploitation of b-catenin signaling as therapeutic target. The proposed studies may potentially have wide implications in designing future therapeutic regimens for the treatments of proteinuric kidney diseases. PUBLIC HEALTH RELEVANCE: It is estimated that up to 13% of the US adult population has some degree of chronic kidney disease (CKD), and the leaks of protein to urine (proteinuria) is an early hallmark and principal pathologic feature of a large number of CKD. The studies proposed in this application promise to provide important insights into understanding the mechanism of proteinuria, and may offer unique opportunities for designing rational strategies for the treatment of human proteinuric CKD.